Year	US Dollars
1970	208775000
1971	407177000
1972	495019000
1973	525580000
1974	505320000
1975	506037000
1976	520751000
1977	675812000
1978	583281000
1979	608637000
1980	719003000
1981	1184523000
1982	1627596000
1983	1867660000
1984	2029275000
1985	2112192000
1986	1984118000
1987	2275813000
1988	2249839000
1989	2316229000
1990	2593897000
1991	2774126000
1992	3788946000
1993	3268514000
1994	2792347000
1995	2505575000
1996	2507364000
1997	2589513000
1998	2712135000
1999	2657225000
2000	2325079000
2001	2047406000
2002	1856715000
2003	1863348000
2004	1769748000
2005	1870907000
2006	1754573000
2007	1530878000
2008	1436379000
2009	1768986000
2010	5987008000
2011	12584092000
2012	14922492000
2013	21609684000
2014	20428665000
2015	20493966000
2016	19688489000